Die casting machine



Feb. 7, 1939. M. STERN DIE CASTING MACHINE Fileddune 9, 1937 6Sheets-Sheet 1 Feb. 7, 1939. M. STERN 2,145,956

DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 2 COMP. AI

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I II 7 p Q: m 21 Feb. 7, 1939. M. STERN 2,145,956

DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 4 Feb. 7, 1939. MSTERN 2,145,956

DIE CASTING MACHINE Filed June 9, 1937 6 Sheets-Sheet 5 M. STERN Feb. 7,1939.

DIE CASTING MACHINE Filed June 9., 1937 Sheets-Sheet 6 Id? ta:

Patented Feb. I, 1939 DIE cAs'rme, MACHINE Marc Stern, Flint, Mich.,assignor to General Motors Corporation, Detroit, Mich, a corporation ofDelaware Application June 9, 1937, Serial No. 147,229

15 Claims.

' number of interrelated parts upon manual initiation are activeaccording to predetermined timing to supply fluid under pressure to thepressure responsive devices.

A further object is to provide a system designed for operation generallyon relatively low fluid pressures and wherein the efiective pressuresare automatically varied in certain steps of the oper- 20 ating cycle.Such variation as affecting relative motion .of the dies, for example,results in an initial slow movement, an accelerated movement in theintermediate range of travel, and a final slow movement so that the diesopen and close 5 quickly and without inertia shock. Additionally, whenthe die is closed and is being filled with molten metal an increasedpressure is built up to hold the die closed and resist separation underinfluence of metal injecting pressures.

30 Additional objects and advantages of the construction will becomeapparent during the course of the following specification havingreference to the accompanying drawings wherein Figure 1 is a sideelevation of the complete machine; Figure 2 35 shows the pair ofpressure pumps driven by the same motor; Figure 3 is a fragmentary view,partly in section, of the metal injecting device; Figure 4 is a diagramof the control system; Figure 5 is a sectional view of the die operatingcylinder; FigiO ure 6 is a sectional view of the ejector assemblyshowing the die in closed position; Figure '7 is a plan view of aportionof the machine; Figures 8, 9 and 10 are perspective views showing theparts which serve to initiate and cut oil? the operation,

block 8 fastened to the upright 3. The sprue opening in the die block 8,as seen in Figure 6, communicates through the nozzle 9 with the pressurechamber I suspended within the melting pot l l. The melting pot tocontain fluid metal forms a part of the furnace l2 which may be fired bya.

gas burner l3 or the like. Molten metal from the .pot ll enters thepressure chamberthrough a 60 passage l4 andis forced by a slidableplunger l into the die cavity. At its upper end the plunger I5 is guidedin a frame l6 and, as shown in Figure 3, is connected by a link I! toone end of a rocker l8 pivoted at I9 on the frame l6 and connected atits opposite end by a link 20 to a connecting head 2| on the rod 22. Therod 22 is joined'to the piston 23 slidable within the cylinder 24 underinfluence'of fluid pressure applied on opposite sides of the piston.

Upon separation of the die blocks the finished casting is pushed out ofthe cavity of the movable die I by an ejector pin 25 which is showninFigure 6 as on the end of ,a rod 26 reciprocable within spacer and diesupporting members 21 on the movable carriage 6. The opposite end of therod 26 is fastened to a slider 28 fixed by a removable pin 29 to thestem 30 of a piston 3| slidable within a cylinder 32 upon theapplication of fluid pressure to one side or the other of the piston.The cylinder is supported upon the movable carriage 6 and the carriageis' fastened by the studs 33 to the piston rod 34 which, as seen inFigure 5, is joined to a piston 35 slidable within a cylinder 36 which.is mounted on the upright 2 and into the opposite ends thereof pressurefluid is introduced for effecting carriage reciprocation.

Fluid, preferably oil, for operating the several work performingcylinders is supplied from a reservoir 31 by a pair of pumps 38 and 39continuously driven by an electric motor 40. The oil under pressureflows through a system of pipes and under control of certain valves putsthe machine through a complete operating cycle. To initiate operationthere is provided a hand lever 4| firmly held in inoperative position bya spring 42' and which lever is mounted at the side of the machinewithin convenient reach of the operator on a rockshaft 43 supported insuitable bearings 44. At its upper end the shaft 43 carries a cam 45which upon manual actuation of the" shaft 43 lifts a pawl 46 about itspivotal mounting on the slide. 41 and against the flat spring 48 out ofalignment with the tip 49 on a spring pressed slide valve 50 containedwithin the valve housing 5| on the upright 2. This allows oil underpressure to reach the ejector cylinder 32 and retract the ejector pin25. Upon move-- lever 54-about its pivot to the position shown in Figure11. The opposite end of the lever engages with the bar 41 and slides itto a predetermined set position for a purpose to be hereinafter referredto.

At the same time that the pawl 46 releases the tip 49, the lever 55 atthe bottom of the rockshaft 43 engages the rod 56 and moves the sameinwardly to shift the slide valve 51 in the casing 58 for deliveringliquid under pressure to the carriage operating plunger. As seen inFigure 4 the rod56 carries a locking collar 58 which moves intoengagement with a pivoted latch 60 which holds the slide valve in setposition against its spring 8| until the latch 60 is released by theaction of a solenoid 62. u Referring more particularly to the diagramvmatic illustration of the control system and assuming the parts havebeen moved by the operation of the hand lever M to the positionsmentioned, oil under pressure will be supplied by the pump 38 throughthe check valve 63 and the conduit 64 to the branches 65 and 65. The

oil flowing through the branch 65 will pass through-the valve casing 5Iand through the conduit 61 to the ram end of the ejector cylinder 32. Atthis time the opposite side of the piston, by means of the conduit 68,is vented through the valve 5I to the drain-pipe 88 which leads back tothe supply reservoir 31.

In the mentioned setting. of the valve 51 oil under pressure supplied bythe branch 86 will flow through the conduit I to a valve casing II andafter lifting the spring seated poppet formations thereon.

pipe 8| leading from the valve casing 82 connected with the pump 38communicates through Means is provided to superimpose pressure from thepump 38 upon that supplied by the pump 39v during the intermediate rangeof carriage travel in order that the travel in this zone may be speededup. For this purpose the carriage has secured'tliereto a strap I5 onwhich'.

are located spaced cam abutments I8 and 11, respectively, the latter ofwhich maybe adjustable. In the first portion of carriage movement thecam I8 engages a roller on a slide valve I8 and moves this valveinwardly in its casing I8 against a spring 80 into position wherein. the

a pipe 83 with a chamber in the valve body 82 on the upper side of apiston valve 84 to close off communication of the pump 38 through theconduit 85' leading to the branch conduit 85. As the movement of thecarriage proceeds the cam I6 moves away from the roller on the slidevalve I8 and allows the valve to be projected under influence of itsspring 80 to a position wherein the pipes 8| and 83 are out ofcommunication and the pipe 83 is drained through the pipe 86.'I'hereupon the pressure from the pump 38 will lift the piston valve 84and oil from the pump a ing carriage.

will flow through the conduit 85 and into the conduits 65and 56 throughthe valve 58 and conduit I0 for action on the piston 35. As the carriageapproaches die closing position the cam II engages with the roller onthe slide valve I8 and again operates the valve to communicate the pipes8I and 83 and thereby close the piston 'valve 84 whereupon the finalmovement is decelerated to cut down the momentum of the slid- As soon asthe die is closed an angle bracket 88 or other suitable part (seeFigure 1) mounted on the carriage 6 engages a button on the switch 88 toclose an electrical circuit which controls the application of pressurefor operating the metal injecting apparatus. The circuit includes a mainline switch 80 and when both switches 88 and 80 .are closed electriccurrent flows through the wire 8| to a relay 92 connected by the wire 83to the return line 94. Actuation of the relay 82 allows current flowthrough the line 95 to a timer 96 of a well known adjustable type. Thereturn line from the timer is indicated at 81. Thereafter for apredetermined interval electric curand back through the return line I00.Actuation of the solenoid 88 moves a slide valve IM to communicate apressure line I02 constituting a branch of the conduit I0 with a valvecylinder I03. This causes the slide valve I04 to move toward the rightin Figure 4 against the spring I 05 and thereafter the pressure line I06leading from the gear pump 38 through the check valve I01, communicateswith a conduit I08 leading to the head end of the cylinder 24, whereuponthe piston 23 is lifted and the plunger I5 is depressed for injectingmetal into the die. x the ram end of the cylinder 24 is vented throughthe conduit I08 by the slide valve I04 to the drain IIO. As soon as oilis supplied by the line I02 to the valve chamber I03 it also flowsthrough the pipe III through a check valve I I2 to a booster cylinder II3 for priming'the same. Concurrently with the flow of oil to the lineI08 oil under pressure is also supplied through the conduit H4 and pasta check valve II5 tothe booster or intensifier cylinder II3. Within thebooster cylinder are interconnected large and small pistons H8 and I II,respectively, and the oil supplied through the line I acting on thelarge piston II6 forces oil at a relatively high pressure through theconduit H8, leading to the valve casing II.- This oil flowing across thevalve I2 closes this valve and acts on the piston 35 to insure the diesbeing held firmly together during the pressure injection of molten metalto the die cavity.

In order that the pressure in the system may be uniform from time totime there is provided an accumulator in the form of a cylinder 8containing a large piston I20 and a small piston I 2I and beneath thesmall piston the cylinder communicates through a conduit I22 with thevalve casing I03 in alignment with the pressure supply line I 06. Theoilcontaining portion of the cylinder, therefore, provides a reservesupply of oil which is under a predetermined pressure through the actionon the large piston I20 from a suitable source of air under pressure.

After a predetermined interval the timer 85 acts to open the circuitcontaining the solenoid- 88 whereupon the valve IOI will be restored andvent the piston cylinder I03 through the drain pipe I23. Thereupon thespring I05 moves the slide valve I04 toward the left in Figure 4 andopens the conduit I08 to the drain pipe I24. At the same time oil "underpressure from the line I08 flows through the conduit I08 and acts on thepiston 23 to restore the same. Thereafter the timer I25 having thereturn line I26 closes a switch between the line I21 and the line I28and through a switch I28 supplies current to the solenoid 82, having areturn line I30 for releasin the latch 60 and allowing the slide valve51 to be restored. As a safety measure the switch I28 precludes closingof this circuit until the metal injecting plunger is fully restored andaccordingly the switch blade has a roller I3I which projects into thepath of and is adapted to .be operated .rent flows through the line 88to a solenoid 88 At the same time.

by the coupling head 2|. As soon as the.valve I1 is restored oil underpressure flows through the line 13 to the ram end of the cylinder 36 forreturning the carriage. At the same time the line III is vented throughthe drain I4 and oil under pressure flows through the pipe I32 and liftsa piston I33 in the casing II which has a stem toengage and open thepoppet valve I2 for communicating the head end of the cylinder 36 withthe conduit Ill. Oil under pressure also flows through the pipe I34 andacts on a piston I36 within the cylinder H3 to engage and hold open thevalve I I6 so that the cylinder may be vented through'the conduit H4 andthe drain pipe I24. The initial return'movement of the carriage is slowand then fast and flnally slow by reason of the engagement anddisengagement successively of the cams 11 and I6 with the valve I8 asbefore referred to.

go As the carriage approaches the final open posi- 25 pipe I36 and oilunder pressure is supplied through the branch 65 and conduit 68 to thehead end of the cylinder 32 for projecting the ejector pin 26. As thepiston 3i moves to its limit the rod 53 carried thereby through anadjustable collar 30 I31 strikes the adjacent end of the lever 64 andcarries this back into latched engagement with the poppet I53.The'swinging of the lever 54 projectsthe pawl 46 an additional amountsufllcient "to move the valve 50 further inward to a position 35 wherebythe pressure supply line 65 communicates with the drain I36. Thus in theinoperative position of the parts a continuous circulation of thepressure fluid is afforded and the reduction in resistance to pumpoperation avoids unnecessary 40 heating of the oil.

It will be .noted among other things, that the operating cylinder 24 forthe metal injector plunger I5 is not mounted directly above the melt-'ing pot as is ordinarily the practice in die casting machines, butrather is mounted at one side.of the furnace and operates the plungerthrough the rocker I8. This eliminates 'a fire hazard due to oil leaksand furthermore enables access to the melting pot for replacementwithout disturbing the operating cylinder and its connections with thefluid pressure lines.

, to be replaced a disconnection is made in the-link' and the plunger"guide frame I6 ismoved out of interference. "For this purpose one ofthe ver-' 55 tical supporting legs of the guide may be swivelly mountedon the furnace assembly as by means of the screw stud I40 and the otherleg is detachably fastened by a similar stud so that the frame can beswung about a vertical axis and to one side.'

0 I claim: 1. Operating mechanism for a die casting machine, including apair of fluid pressure actuated operating units operable, respectively,to close the die and to inject molten metal into the closed die,

5 a source of pressure fluid adapted for communication with the unitwhich operates to inject metal into the die, a second source of pressurefluid adapted for communicationjwith the die 7 closing unit; and meansactive after a predeter- 7 mined response of the last mentioned unitfrom fluid pressure supplied by said second source to communicate thefirst mentioned source of pressure with said last mentioned unit.

2. In a die casting machine, a pair of relatively 7 movable diemembers,a fluid pressure operated When the melting pot is device associated withsaid members for eflecting their relative movement, means to supplypressure fluid to said device including a pair of pumps. meansto-connect one of said pumps with said device throughout the range ofmovement and means active in a predetermined intermediate I fluidpressure to operate the last mentioned device, a second source ofpressure fluid independent of said first mentioned source to operate thefirst 15 mentioned device and means active within a predeterminedintermediate portion of the stroke of the first mentioned device tosuperimpose pressure fluid from the flrst source on that supplied by thesecond source for accelerating the opera- 20 tion of said device.

4. In a die casting machine, a die operating piston, a cylindercontaining said piston, a pair of conduits leading to opposite ends ofthe cylinder,

a two-way valve adapted to communicate either of said conduits with asource of low pressure fluid and concurrently vent the other conduit, acheck valve in one of said conduits adapted to be opened by fluid flowthrough the conduit to the cylinder, a high pressure line leading to theend of the cylinder beyond said check valve so that fluid flowtherethrough closes said check valve, a fluid pressure actuated valveoperating device to open ,said check valve and means to supply pressurefluid to said device when said two-way valve vents the conduitcontaining the check valve and communicates the other conduit with saidsource of pressure fluid. 1

5. In a die casting machine, a die operating device movable in oppositedirectionswithin a chamber in response to pressure differential onopposite sides thereof, a pair of conduits communicating with thechamber on opposite sides of said device, a two-way valve to connecteither conduit with a source of fluid pressure and concurrently drainthe other conduit, a check valve in one of said conduits, a fluidpressure actuated booster connected beyond said check valve, means tosupply actuating fluid pressure to the booster,

a check valve associated with said means, pressure actuated devicesassociated with both check valves to open the same, and means activethrough said two-way valve when the conduit containing the check valveis being drained to supply actuating fluid to both of said pressureactuated devices.

6. In a die casting machine, a frame, a reciprocatory carriage on theframe for opening and closing a die, a pressure fluid actuated devicemounted on the carriage for performing a service co operation, a valvemounted on the frame for supplyingfluid pressure to said device, a pawlslidable on the carriage to engage a valve operating member to set thesame in either of two positions, one of which completes a circuit forthe pressure 35 'fluid, and the other of which supplies fluid pressureto oneside of said device, means for'tripping the pawl to set the valvein a third position for supplying fluid pressure to the other side ofthe device and means connected with the pawl and 7 movable with thepressure responsive device after tripping the pawl to slide the pawl toa setting for engagement, upon the return strokeof the carriage, withtheva-lve operating member and thereby move the valveto the secondmentioned 7 position, and upon response of said device to such valvesetting to slide the valve in the opposite direction and thereby setsaid valve in the first mentioned position.

7. In a die casting machine,control mechanism for a fluid pressuredevice which moves the die between opened and closed positions,including, a two-way valve to supply fluid pressure to said device,means biasing the valve toward die opening position, means for shiftingthe valve manually to die closing position, latch means to hold thevalve in its manually set position, an electrically actuated device torelease the latch, timing mechanism controlling the actuation of saidlatch releasing device, and a switch to set the timing mechanism intoaction automatically when the die is closed.

8. In a die casting machine, a reciprocable die actuating device movablein response to pressure diiferential on opposite sides thereof, atwo-way valve adapted when in one position to supply fluid pressure onone side of the device to close the die and when in the other positionto supply pressure fluid to the other side of the device to open thedie, means responsive to pressure differential on opposite sides thereofto depress and retract a' metal feeding plunger, a two-way valve tosupply operating fluid pressure on either side of said means, manualmeansto set the first valve in die closing position, a releasable latchto retain the valve in its manually set position, means de-' pendentupon die closing position of the first device automatically to set thesecond valve in plunger depressing position, timing mechanism to rendersaid setting means inefiective so as, to set the valve in plungerretracting position, addi-' vice, a fluid pressure actuated valveoperable to connect said pressure fluid source with both the lastmentioned device and the booster, secondary valve means operable toconnect said pressure fluid source with both the booster and saidpressure actuated valve and means acting automatically when the die isclosed to operate the secondary valve means.

10. Control mechanism for a die casting machine, having a movable diecarriage and a fluid pressure actuated ejector mechanism mounted on saidcarriage, a valve operating plunger adapted when in one position tocommunicate said ejector mechanism with a source of operating fluid andwhen in another position to by-pass said mechanism, a projectibleabutment on said carriage adapted to engage said plunger coincident withcarriage movement to move the same to the first mentioned position andmeans operating in response to said ejector mechanism to project saidabutment for moving the plunger to the second mentioned position.

11. Control mechanism for the sequential operation of the fluid pressureactuated devices of a die casting machine, including a fluid pressureactuated valve' adapted upon pressure fluid application thereon tosupply operating pressure fluid to metal injecting means and to abooster associated with die closing means, a control valve adapted whenopen toflow operating pressure fluid to the booster and the firstmentioned valve,

amaster valve adapted when manually set ;to supply operating pressurefluid to the die closing means and through said control valvetothefirst] sure fluid to metal injecting means and to a pressure fluidbooster associated with die closing means, a-valve controllingpressurefluid flow to the fluid pressure actuated valve for its actuation and tothe booster in advance of the supply from the pressure actuated valve,means operated automatically to open said control valve when the die isclosed, and a manually set valve adapted to supply pressure fluid to adie closing means and through said control valve to the pressureactuated valve and the booster.

13. In a die casting machine, a source'of fluid pressure, die closingmeans and metal injecting means, both operated by pressure fluid fromsaid source, a fluid pressure actuated booster associated with the dieclosing means to increase fluid pressure thereon, a fluid pressureactuated valve adapted to communicate the pressure fluid sourcesimultaneously with both the metal injecting means and the booster uponthe application thereon of pressure fluid, a manually set valve adaptedwhen in manually set position to communicate the pressure fluid sourcesimultaneously with the die closing means and said fluid pressureactuated valve, an electrically actuated valve interposed between saidvalves and adapted when actuated to pass pressure fluid simultaneouslyto the fluid pressure actuated valve and to the booster and meansactuated by the die closing means when in die closing position to supplycurrent to said electrically actuated valve.

14. In a die casting machine, a movable die carriage, a fluid motortherefor, a pair of pumps for supplying pressure fluid to said motor, avalve controlling fluid flow from one of the pumps,

and a valve operating cam bar supported by the carriage and having valveclosing camrning abutments spaced apart .and active on the valve near Oposite limits of carriage travel.

15. Control mechanismfor a die casting machine including a valve casingmounted on a stationary part of the machine, a valve operating plungermovable to any one of three positions to control flow of pressure fluidin bne position to project an ejector mechanism carried by a mov abledie carriage, in another position to retract .said mechanism and in thethird position'to bypass said mechanism, a projectible abutment on thecarriage to engage said plunger and move the same coincident to carriagemovement to its ejector projecting position, means movable with theejector mechanism to project said abutment for moving the plunger to itsby-passing position and a manually operated trip device to disengage theabutment and plunger for plunger movement to ejector retractingposition.

' MARC STERN.

